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sev: Provide sev_features flags from IGVM VMSA to KVM_SEV_INIT2

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IGVM files can contain an initial VMSA that should be applied to each
vcpu as part of the initial guest state. The sev_features flags are
provided as part of the VMSA structure. However, KVM only allows
sev_features to be set during initialization and not as the guest is
being prepared for launch.

This patch queries KVM for the supported set of sev_features flags and
processes the VP context entries in the IGVM file during kvm_init to
determine any sev_features flags set in the IGVM file. These are then
provided in the call to KVM_SEV_INIT2 to ensure the guest state
matches that specified in the IGVM file.

The igvm process() function is modified to allow a partial processing
of the file during initialization, with only the IGVM_VHT_VP_CONTEXT
fields being processed. This means the function is called twice,
firstly to extract the sev_features then secondly to actually
configure the guest.

Signed-off-by: Roy Hopkins <roy.hopkins@randomman.co.uk>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Gerd Hoffman <kraxel@redhat.com>
Tested-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/b2f986aae04e1da2aee530c9be22a54c0c59a560.1751554099.git.roy.hopkins@randomman.co.uk
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Roy Hopkins 2025-07-03 17:21:59 +01:00 • committed by Paolo Bonzini
parent 2ff75825cc
commit d60238b4c1
6 changed files with 163 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

17
backends/igvm.c
View file

@ -880,7 +880,7 @@ static IgvmHandle qigvm_file_init(char *filename, Error **errp)
}
int qigvm_process_file(IgvmCfg *cfg, ConfidentialGuestSupport *cgs,
Error **errp)
bool onlyVpContext, Error **errp)
{
int32_t header_count;
QIgvmParameterData *parameter;
@ -924,11 +924,22 @@ int qigvm_process_file(IgvmCfg *cfg, ConfidentialGuestSupport *cgs,
ctx.current_header_index++) {
IgvmVariableHeaderType type = igvm_get_header_type(
ctx.file, IGVM_HEADER_SECTION_DIRECTIVE, ctx.current_header_index);
if (qigvm_handler(&ctx, type, errp) < 0) {
goto cleanup_parameters;
if (!onlyVpContext || (type == IGVM_VHT_VP_CONTEXT)) {
if (qigvm_handler(&ctx, type, errp) < 0) {
goto cleanup_parameters;
}
}
}
/*
* If only processing the VP context then we don't need to process
* any more of the file.
*/
if (onlyVpContext) {
retval = 0;
goto cleanup_parameters;
}
header_count =
igvm_header_count(ctx.file, IGVM_HEADER_SECTION_INITIALIZATION);
if (header_count < 0) {

2
backends/igvm.h
View file

@ -17,6 +17,6 @@
#include "qapi/error.h"
int qigvm_process_file(IgvmCfg *igvm, ConfidentialGuestSupport *cgs,
Error **errp);
bool onlyVpContext, Error **errp);
#endif